A passive optical network (PON) is one system for providing network access over “the last mile.” The PON is a point-to-multi-point (P2MP) network comprised of an optical line terminal (OLT) at the central office, an optical distribution network (ODN), and a plurality of optical network units (ONUs) at the customer premises. Ethernet passive optical network (EPON) is a PON standard developed by the Institute of Electrical and Electronics Engineers (IEEE) and specified in IEEE 802.3ah, which is incorporated herein by reference as if reproduced in its entirety. In EPON, a single fiber can be used for both the upstream and the downstream transmission with different wavelengths. The OLT implements an EPON Media Access Control (MAC) layer for transmission of Ethernet Frames. The Multi-Point Control Protocol (MPCP) performs the bandwidth assignment, bandwidth polling, auto-discovery, and ranging. Ethernet frames are broadcast downstream based on the Logical Link Identifier (LLID) embedded in the preamble frame. Upstream bandwidth is assigned based on the exchange of Gate and Report messages between an OLT and an ONU.
In addition to EPON, other protocols may be implemented in a PON. Examples of such protocols include the asynchronous transfer mode (ATM) PON (APON) and the broadband PON (BPON) defined by the International Telecommunications Union (ITU) Telecommunication Standardization Sector (ITU-T) G.983 standard, Gigabit PON (GPON) defined by the ITU-T G.984 standard, and the wavelength division multiplexing (WDM) PON (WDM-PON).
With an increasing need for open access, PON systems comprising multiple OLTs are appearing. A multi-OLT PON can enable a plurality of service providers to share infrastructure. However, a multi-OLT PON system presents complications in the coordination and control of the various OLTs. Consequently, there is a need in the art for methods and apparatus for inter-OLT communication and control.